Pensions taxed at source and declarations

Are French pensions – the state pension, as well as supplementary pensions – taxed at source or do I need to declare them?

The answer is that both apply. You should declare your French pensions even though they will already have had tax taken off at source. The tax office will note the tax that has already been levied and will not charge it again. 

Essentially, you declare all of your worldwide income – apart from a few exceptions such as income from regulated tax-free French savings accounts.

The tax office will then check to see if you have already paid enough (or too much) in at-source tax.